Beams continued

Autumn is well and truly upon us here in Tas. The days are becoming shorter and there is a chill in the air in the mornings. So far, however the settled conditions we have experienced for the last couple of months have continued, with light variable winds from the NE on most days. We were unaffected by cyclone Debbie this far south, but our thoughts were with the people of QLD and northern NSW. Extreme weather events seem to be more frequent these days.

This week we have pushed on with joining the hulls together, by focusing on frames three five and nine. These are scarfed together then offered up to their corresponding frames built into the hulls. They ensure the hulls are vertical and correctly spaced apart and are the final check that the hulls are set up properly. We were relieved they slotted into place perfectly.

Initially there are three main beams that connect the hulls. Later in the build three additional beams or bulkheads are constructed for varying purposes, so ultimately there are six spans that cross the hulls. In addition the upper deck and lower bridge-deck combine to lock the entire structure together, making a very rigid boat.

The assemblies we are constructing at this point are critical load bearing structures, so we are taking our time and making frequent calls to the designer with any queries we may have along the way. Each beam is constructed differently depending upon its load, or to reduce the impact on internal accommodation spaces. Modern catamaran design has evolved to the point where these heavy structural elements are incorporated into the walls of the cabins and are not apparent to the casual observer. It’s also why, if considering purchasing a second-hand cat, you should be wary of modified or “custom” builds that have strayed from the original design.

Frame three glued off.
Glulam beam atop Frame 3 completed. This is constructed of four 42 x 18 profiles laminated into a curve.
Gluing up the first of the glulam laminations.
Hulls set up in final positions, ready for gluing off. The bridge-deck Deb is standing on is lifted to join the bottom of the frames.

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